Not applicable.
1. Field of the Invention
The present invention relates generally to a disk drive including an air bearing slider including a pressurized pad separated from a contact pad that is in sliding contact with a magnetic disk.
2. Description of the Prior Art
The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the, HDA. The head disk assembly includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA). The spindle motor includes a spindle motor hub that is rotatably attached to the disk drive base. The hub has an outer hub flange that supports a lowermost disk. Additional disks may be stacked and separated with annular disk spacers that are disposed about the hub. The head stack assembly has an actuator assembly including at least one air bearing slider or head, typically several, for reading and writing data to and from the disk. Each air bearing slider includes a magnetic transducer. An example of a slider is disclosed in U.S. Pat. No. 5,473,485 (incorporated herein by reference) that describes a tri-pad slider where a center pad contains a transducer. The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk.
The head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit cable assembly. A conventional xe2x80x9crotaryxe2x80x9d or xe2x80x9cswing-typexe2x80x9d actuator assembly typically includes an actuator body that has a bore and a pivot bearing cartridge engaged within the bore for facilitating the actuator body to rotate between limited positions. The actuator assembly further includes a coil portion that extends from one side of the actuator body to interact with one or more permanent magnets to form a voice coil motor. One or more actuator arms extend from an opposite side of the actuator body. A head gimbal assembly includes an air bearing slider that is attached to a suspension with a gimbal. Head gimbal assemblies are distally attached to each of the actuator arms. The head gimbal assemblies and the flex circuit cable assembly are attached to the actuator assembly.
In order to increase the amount of data that may be stored upon a given disk, the recording density of the tracks of the magnetic disks has increased steadily. As such, it has become necessary within the field of hard disk drives to xe2x80x9cflyxe2x80x9d the magnetic transducer closer to the magnetic disk. By way of illustration, referring now to FIG. 1, there is depicted a prior art air bearing slider 1. The prior art air bearing slider 1 includes leading and trailing sides 2, 3. A center pad 4 extends from a main support structure 5. The center pad 4 includes an air bearing surface 6. A transducer 7 is disposed within the center pad 4 adjacent the trailing side 3. The prior art air bearing slider 1 further has a pair of main rails 8, each having an air bearing surface 9. Typically, the slider 1 is configured to fly with the trailing side 3 (and therefore the transducer 7) close to the disk surface without contacting the disk surface.
While the air bearing slider 1 may be configured such that the trailing side 3 is in contact with the disk surface for minimizing the distance between the transducer 7 and the disk surface, significant wear problems associated with the slider 1 and the disk surface are introduced. Operated in this manner, air pressure along the slider 1 progressively increases towards the trailing side 3. Thus a large amount of air pressure is built up against the center pad 4. To maintain the contact of center pad 4 at trailing side 3 with the disk, a xe2x80x9ccontact forcexe2x80x9d is introduced within the contact area. The amount of this contact force equals to the difference between preload of the suspension and the force generated by the air pressure outside the contact area. Using a highly pressurized area as the contact area results in a relatively higher contact force. Such a relatively higher contact force results in excessive wear of the center pad 4 and the disk that eventually results in damage to the same. Accordingly, there is a need in the art for an improved air bearing slider arrangement in comparison to the prior art.
An aspect of the invention can be regarded an air bearing slider for use in disk drive that includes a rotatable magnetic disk. The slider includes a leading side and a trailing side. The slider further includes a pressurized pad including a pressurized pad air bearing surface. The pressurized pad is disposed between the leading and trailing sides. The slider further includes a contact pad disposed adjacent the trailing side and including a contact surface for sliding contact with the magnetic disk during operation of the disk drive. The contact pad includes a transducer disposed within the contact pad for reading and writing data from and to the magnetic disk. The slider further includes a depressed region disposed between the pressurized pad and the contact pad for mitigating air pressure adjacent the contact surface relative to air pressure adjacent the pressurized pad air bearing surface during operation of the disk drive.
According to an embodiment of an aspect of the present invention, the contact surface is preferably sized smaller than the pressurized pad air bearing surface. The air bearing slider may further include first and second main rails disposed between the leading and trailing sides. The first main rail has a first main rail air bearing surface, and the second main rail has a second main rail air bearing surface. The pressurized pad is disposed between the first and second main rails. The pressurized pad and the contact pad may be centered with respect to the first and second main rails. Alternatively, the pressurized pad and the contact pad may be biased towards a respective one of the first and second main rails. The pressurized pad may additionally be integrally formed with the respective one of the first and second main rails.
In another embodiment, the air bearing slider may further include a pressurized pad support base and the pressurized pad may extend from the pressurized pad support base. The contact pad may also extend from the contact pad support base. The contact pad may extend from the contact pad support base by about 0.1 to 0.3 microns. The pressurized pad support base and the contact pad support base may be integrally formed, with the depressed region extending from the pressurized pad support base and the contact pad support base.
In another embodiment, the air bearing slider may further include a main support structure. The pressurized pad support base and the contact pad support base may extend from the main support structure, and the depressed region may extend from the main support structure between the pressurized pad support base and the contact pad support base. The pressurized pad support base and the contact pad support base may extend from the main support structure by about 1 to 3 microns.
In yet another embodiment, the air bearing slider may further include a pressurized pad support base and a main support structure. The pressurized pad may extend from the pressurized pad support base, and the pressurized pad support base and the contact pad may extend from the main support structure.
The depressed region may extend from about 50 to about 300 microns between the pressurized pad and the contact pad.
According to additional aspects of the present invention, the above-described air bearing slider may be incorporated into a disk drive.